Conventionally, an induction heating cooking apparatus of this kind includes a top plate for placing a cooking container thereon, a heating coil disposed below a location where the cooking container is placed, a magnetic flux-shielding member disposed in the vicinity of the heating coil to restrain magnetic flux leakage from the heating coil, an infrared sensor for receiving infrared rays emitted from the cooking container on the top plate and outputting a detection signal depending on the amount of light received, and a control circuit for controlling an output of the heating coil based on the detection signal, wherein the infrared sensor is positioned below the magnetic flux-shielding member (see, for example, Patent Document 1).
FIG. 6 depicts a conventional induction heating cooking apparatus, which includes a main body 1 forming an outer shell, a top plate 3 mounted on an upper surface of the main body 1 to place a cooking container 2 thereon, and a heating coil 4 disposed below the top plate 3 to induction heat the cooking container 2. A plurality of ferromagnetic ferrite materials 5 having a magnetic flux-collecting effect are disposed below the heating coil 4 so as to extend radially from a center of the heating coil 4, as viewed from above, to control magnetic flux that is directed downwardly from the heating coil 4.
An infrared sensor 6 is disposed below the heating coil 4 that induction heats a bottom surface of the cooking container 2. The infrared sensor 6 detects infrared rays emitted from the bottom surface of the cooking container 2 through the top plate 3 and outputs a signal depending on a temperature of the bottom surface of the cooking container 2. A control circuit 7 is disposed below the infrared sensor 6 to control an output of the heating coil 4 based on the signal outputted from the infrared sensor 6.
The control circuit 7 is accommodated within a cooling air trunk 11 defined between a bottom wall of the main body 1 and a partition plate 10 disposed below the heating coil 4. Heat-generating components 8 constituting the control circuit 7 such as an IGBT mounted to a heat sink 8a, a resonance capacitor, and the like are fixedly mounted on a control board 7a and cooled to a desired temperature by a fan 9 mounted in the main body 1.
The heating coil 4 is placed on an upper surface of a coil base 13, in which the ferrite materials 5 are accommodated, and fixed thereto, for example, by bonding. The coil base 13 is supported by a plurality of springs 12 mounted on the partition plate 10 and is pressed against a lower surface of the top plate 3 by the springs 12 via a spacer 16 that provides a space between an upper surface of the heating coil 4 and the top plate 3. The infrared sensor 6 is disposed below the ferrite materials 5 and above the partition plate 10. The influence of magnetic flux on the infrared sensor 6 is reduced by the magnetic flux-collecting effect of the ferrite materials 5.
Further, in order to eliminate the influence of magnetic flux leakage, the infrared sensor 6 is encircled by a magnetic flux-shielding casing 14 made of, for example, aluminum and having a magnetic flux-shielding effect. The infrared sensor 6 must be cooled to a desired temperature, because the infrared sensor 6 is heated and the temperature thereof increases by heat generated from the heating coil 4 and the cooking container 2. To this end, the partition plate 10 has a vent hole 15 defined therein in the vicinity of the infrared sensor 6, and part of cooling air passing through the cooling air trunk 11 passes through the vent hole 15 to cool the infrared sensor 6.
By this construction, the conventional induction heating cooking apparatus having the infrared sensor can conduct stable temperature detection with the use of the infrared sensor without being affected by the magnetic flux leakage from the heating coil.